Are M96s inherently flawed design-wise? Or were there just bad batches

[bimmerhead]

Hello! I have been a bimmer enthusiasts for many years now and am obsessed with taking the plunge on a local 99 996 with 10k miles on a new crate motor installed in 07 (so should incorporate all the updates on the engine). I know that there have been many threads about this subject, but please bear with me as I have a specific (somewhat involved) question.

From that long thread over at pistonheads recording engine failures, the main conclusion that "Hartech" seems to have come to with rebuilds of M96s is that due to inherent design issues that have not been rectified in any of the updated engines, a small percentage of M96s are essentially ticking time bombs - due to the lokasil cylinder liners which eventually go out of spec and oval out as well as cylinder wall thickness, all of which will lead to cracked cylinder walls and coolant/oil intermix. I am no engineer but his reasoning appears sound, and though there is a bit of a ulterior motive in terms of selling his revised cylinder liners, he is one of a few companies that offer this as a lower cost and more reliable alternative for a rebuild.

http://www.pistonheads.co.uk/gassing/topic...!&mid=0

However, this oft quoted article from Excellence seems to argue the opposite as their engine teardown at 100k miles showed that cylinder wear was almost non-existant - which I'm going to assume means to "ovaling".

http://www.renntech.org/forums/index.php?a...ost&id=3224

These two assumptions seem to contradict each other, so I am quite confused - which is right? Who do we trust?

Has the porsche community come to any conclusion on what really is causing failures on many M96s? Is it inherent engineering faults or just a bad batch of motors? What muddies the waters even more are these stories that the earlier engines were affected by poor castings from the factory.

I know what some of you will say, just buy it and enjoy driving it, but with the cost of replacement engines now coming close to the purchase price of a 99-00 911 C2, it seems like a foolhardy chance to take - if rebuilds were more reasonably priced than it would be a different thing, but then we go into issue of resale on a car with a rebuilt engine rather than a new factory crate motor - which to the passing buyer would seem less attractive even though you could incorporate design fixes in a rebuild that would still exist in the crate motor.

Edited May 1, 2009 by bimmerhead

[Benjamin Choi]

Hello! I have been a bimmer enthusiasts for many years now and am obsessed with taking the plunge on a local 99 996 with 10k miles on a new crate motor installed in 07 (so should incorporate all the updates on the engine). I know that there have been many threads about this subject, but please bear with me as I have a specific (somewhat involved) question.

From that long thread over at pistonheads recording engine failures, the main conclusion that "Hartech" seems to have come to with rebuilds of M96s is that due to inherent design issues that have not been rectified in any of the updated engines, a small percentage of M96s are essentially ticking time bombs - due to the lokasil cylinder liners which eventually go out of spec and oval out as well as cylinder wall thickness, all of which will lead to cracked cylinder walls and coolant/oil intermix. I am no engineer but his reasoning appears sound, and though there is a bit of a ulterior motive in terms of selling his revised cylinder liners, he is one of a few companies that offer this as a lower cost and more reliable alternative for a rebuild.

http://www.pistonheads.co.uk/gassing/topic...!&mid=0

However, this oft quoted article from Excellence seems to argue the opposite as their engine teardown at 100k miles showed that cylinder wear was almost non-existant - which I'm going to assume means to "ovaling".

http://www.renntech.org/forums/index.php?a...ost&id=3224

These two assumptions seem to contradict each other, so I am quite confused - which is right? Who do we trust?

Has the porsche community come to any conclusion on what really is causing failures on many M96s? Is it inherent engineering faults or just a bad batch of motors? What muddies the waters even more are these stories that the earlier engines were affected by poor castings from the factory.

I know what some of you will say, just buy it and enjoy driving it, but with the cost of replacement engines now coming close to the purchase price of a 99-00 911 C2, it seems like a foolhardy chance to take - if rebuilds were more reasonably priced than it would be a different thing, but then we go into issue of resale on a car with a rebuilt engine rather than a new factory crate motor - which to the passing buyer would seem less attractive even though you could incorporate design fixes in a rebuild that would still exist in the crate motor.

If your '99 comes with a reman motor from Porsche, then I wouldn't worry about all that other stuff cuz all you would be doing is losing hair over something you no longer need to care about. I've rarely, if ever, heard of a reman engine failing unlike the originals. Again, just make sure it's a reman engine from Porsche factory.

Myself, I would never buy or recommend to a potential buyer an original "engined" MK1 996. I have less concerns when it comes to the 3.6 motor in the MKIIs, but still prefer a reman over original in all cases.

No one but Porsche has the answer to the question you pose. Porsche has been and will be tight-lipped about their engine issues. So much for the awesome German engineering! I'm certainly not a Porsche snob, but very much a realist. All manufacturers have their pros/cons. Nobody's perfect. No car is perfect.

Edited May 1, 2009 by Benjamin Choi

[bimmerhead]

yeah risks involved with any high performance machine - my other choice, an E46 M3 has had reports of vanos and various bearing failures - I'm wondering if the reason why there hasn't been as strong as a response by the online community because BMW owned up to it eventually, whereas porsche just basically left people hanging..

[BruceP]

I have never been fool enough to believe that "most expensive" equals "best". Or that "best" equals "most durable/reliable", for that matter. You accept certain risks when you buy a low volume vehicle. You accept a few more when you buy an engine as experimental as this was for Porsche, and a few more when you remember that the M96 was assembled by hand at a bench. And you accept a few more when you buy a car from a company in financial trouble, which Porsche was when the 996 was developed.

Take all that into account, and I think that it's amazing how potent and reliable this engine and car are. For me, there is only one problem worth losing any sleep over, and that's the intermediate shaft, a risk that was designed into the engine. The rest of what you hear are either just annoying (like the RMS is) or rumors based on muddled facts (like the slipped sleeve and porous block issues, which were quickly resolved in the 986 before the 996 was sold).

Fortunately for buyers, all of this risk and more has already been priced into the used car market. A lot of 996s now are objectively screaming deals, even budgeting for a new motor.

[JeTexas]

For every story on this forum discussing a bad engine, there's another user with an original engine that passed 100,000 miles with no problems. Then you have to realize what a small sampling you're actually getting of total Porsche owners since very few take the time to read/post to the forums or work on their cars themselves.

Trying to look at the situation from an objective outside point of view, I don't think Porsche had any more trouble with their M96 engines than say Ford did when it introduced the modular 4.6. However, the issue that comes into play is how much more expensive it is to replace an M96 should something go wrong.

[Benjamin Choi]

yeah risks involved with any high performance machine - my other choice, an E46 M3 has had reports of vanos and various bearing failures - I'm wondering if the reason why there hasn't been as strong as a response by the online community because BMW owned up to it eventually, whereas porsche just basically left people hanging..

it's not the same thing.

the vanos/rod issue on the S54, i believe, impacted far less engines than the M96. you don't have an RMS, IMS leak, IMS bearing failure, coolant/oil intermix deal with the S54. it is what i would call a bulletproof engine, very rare to hear of failures esp after the offical TSB by BMW plus the wonderful extended engine warranty.

porsche should've been forthright like bmw s54, but they were and are tight lipped about it and it just causes greater anxiety for current owners and potential buyers.

[Benjamin Choi]

Fortunately for buyers, all of this risk and more has already been priced into the used car market. A lot of 996s now are objectively screaming deals, even budgeting for a new motor.

Agreed and I'd for further by extending that to ALL cars. If you have cash, go buy what you've always wanted to buy. AMG, M, Ferraris, RS, etc. It'll be like this in autodom for quite some time.

But I would never advise someone to go out and buy an original engine MK1 996. It'll cost you $25K to get into a water-cooled 911, but you're potentially staring at a $12-15K bill for a reman Porsche factory engine + labor and this price will never go down.

[BruceP]

Fortunately for buyers, all of this risk and more has already been priced into the used car market. A lot of 996s now are objectively screaming deals, even budgeting for a new motor.

Agreed and I'd for further by extending that to ALL cars. If you have cash, go buy what you've always wanted to buy. AMG, M, Ferraris, RS, etc. It'll be like this in autodom for quite some time.

But I would never advise someone to go out and buy an original engine MK1 996. It'll cost you $25K to get into a water-cooled 911, but you're potentially staring at a $12-15K bill for a reman Porsche factory engine + labor and this price will never go down.

Additional depreciation on a newer car is real money, too. And it's not a risk, it's a certainty. All a matter of how you want to pay the piper, but the piper will be paid. It's a Porsche.

[Benjamin Choi]

we can split hairs over depreciation and $ figures all day but at the end of the day, it's not just $15K out the door... it's $15K worth of time and energy lost on something one should never have to go thru in the first place. it's not just a porsche. it's $15K you could spend on something that's just as memorable or better like a nice vacation with loved ones or a white face rolex daytona plus a panerai luminor to round out the collection v. spending it on an engine on a car that should've come with one that works reliably in the first place - it's a Porsche right?

to the Op, i wouldn't hesitate to get a reman mk1 996 assuming all else checks out. your chances of another failure are slim.

Edited May 7, 2009 by Benjamin Choi